Fire protection system

ABSTRACT

Disclosed is a fire protection system including a plurality of suppressor units activatable to suppress a detected fire; a plurality of electrical current responsive activators, one associated with each of the suppressor units and adapted to induce activation thereof; a control circuit connecting the activators in series and including an actuator for initiating activating current flow to the activators; and an auxiliary circuit comprising switch means for connecting the activators in parallel in response to the initiation of activating current flow by the actuator.

United States Patent 1191 Davis et al.

[ Nov. 4, 1975 FIRE PROTECTION SYSTEM 7 [75] Inventors: Robert F. Davis, Framingham; Carl g m g l g if i I. Swanson, Boylston, both of Mass. smtam xammer 1c ae ax Attorney, Agent, or Fzrm-John E. Toupal [73] Assignee: Walter Kidde & Co., Inc., Clifton,

[57] ABSTRACT [22] Flled: 1974 Disclosed is a fire protection system including a plu- [21] Appl. No.: 500,864 rality of suppressor units activatable to suppress a detected fire; a plurality of electrical current responsive activators, one associated with each of the suppressor [2%] Coll 169/61; 169/28; 340/253 B units and adapted to induce activation thereof; a com d A62C 37/04 trol circuit connecting the activators in series and in- 1 le 0 c eluding an actuator for initiating activating current 169/28 340/418 253 B flow to the activators; and an auxiliary circuit comprising switch means for connecting the activators in [56] References Clted parallel in response to the initiation of activating cur- UNITED STATES PATENTS rent flow by the actuator.

2,373,819 4/1945 Eaton 169/28 2,814,795 11/1957 Spooner 340/253 B 12 Chums 1 D'awmg F'gure l8 lll fi l FIRE N 22W DELA Y Kl SUPPRESSOR UN T SOURCE K /2\ SUPPRESSOR L UN/T K2 F/ RE N, I l2 SUPPRESSOR UNIT FIRE PROTECTION SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to fire protection systems and, more particularly, to fire protection systems in which a plurality of individual fire suppressor units are simultaneously activated to extinguish a fire.

Certain fire protection systems employ a plurality of strategically located suppressor units, each including an extinguishant filled vessel and an electrically operated release mechanism for inducing discharge of the extinguishant in response to detection of a fire. When simultaneous operation of all suppressor units is desired, the system is provided typically with a control circuit that produces coincident activation of all release mechanisms. In such systems, it is common technique to electrically supervisethe electric integrity of the release mechanisms by providing and monitoring a trickle current through a series connection thereof. Although this series supervision establishes a constant knowledge of release mechanism integrity, there remains the possibility that a single release member failure will cause failure of the entire series system. In addition, even a detected failure of a release mechanism SUMMARY OF THE INVENTION The present invention provides a fire protection system including a plurality-of suppressor units activatable to suppress a detected fire; a plurality of electrical current responsive activators, one associated with each of said suppressor units and adapted to induce activation thereof; a control circuit connecting the. activators in series and including an actuator for initiating activating current flow to the activators; and an auxiliary circuit comprising switch means for connecting the activators in parallel in response to the initiation of activating current flow by the actuator. Because of the switching provided by the auxiliary circuit, all functional activators will operate even in the event that a single activator fails in such a way as to prevent normal series operation of the system.

In a preferred embodiment of the invention, the individual suppressor units comprise vessels filled with a fire suppressing agent that is released by activation of an explosive squib. The actuator is a device that initates current flow to the series connected activator squibs and can be either a manually operated switch or a condition responsive device such as a thermal switch, or a products-of-combustion detector.

Another feature of the invention is the provision of a delay for the auxiliary circuit that ensures normal series operation of the individual activators in the absence of any individual failure thereof that would prohibit such operation.

DESCRIPTION OF THE DRAWING These and other objects and features of the present invention will becomemore apparent upon a perusal of the following description taken in conjunction with the accompanying drawing, which is a schematic circuit diagram illustrating a preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, there are shown a plurality of vessels filled with a suitable fire extinguishing agent and distributed strategically throughout a fire protected zone. Each of the vessels 11 is provided with an explosive squib 12 that is detonated by electrical current flow to induce release of the agent contained in the associated vessel '11. The vessels 11 and activators 12 are conventional and of a type, for example, disclosed in US. Pat. Nos. 2,693,240 and 3,523,583. Connecting the activators 12 in series with a power source 13 is a control circuit that includes an actuator switch 14. Although the actuator 14 can be a simple manual switch, it preferably comprises a condition responsive sensor that closes the circuit between the power source 13 and the activators 12 in-response to detection of a given abnormal condition such as fire. Suitable condition responsive sensors include, for example, thermal switches such as disclosed in US. Pat. Nos. 2,537,028 and 3,423,585. Connected in series between activators l2 and the power source 13 is a supervisory network including a relay coil 16 that provides a limited supervisory current flow through the activators 12. Operated by the coil 16 are normally-closed contacts 17 connecting a power supply 18 and an indicator light 19.

An auxiliary control circuit 21 includes a plurality of normally open contacts K1 and K2 that, when closed, connect the activators 12 in parallel across the power source 13. Controlling the contacts K1 and K2 is a relay coil K connected in series with a delay circuit 22 across the actuator 14 and the power source 13.

During normal operation, a supervisory current of, for example, 5-10 milliamps flows through the activators 12 and the relay l6 maintaining the contacts 17 open and the indicator light 19 de-energized. However, any failure such as an individual activator with an abnormally high resistance that would prevent activating current flow through the series-connected activators 12 also will reduce supervisory current flow to less than the holdin level for the winding 16, allowing the contacts 17 to close and thereby energize the indicator lamp 19. Having observed the energized light 19, maintenance personnel can examine the control circuit and correct the fault to regain system integrity.

In response to an abnormal environmental condition such as fire, the closing of the switch, either manually or by a suitable sensor, will initiate activating current flow and thus coincidentally activate all of the activator devices 12. Also, when the switch 14 is closed, the Delay 22 is activated. Upon expiration of the specified delay, the relay coil K will activate, resulting in the closing of the relay contacts K1 and K2. These contact closures transfer the activators 12 from their initial series connection into a parallel connection with the result that they are not independently placed in parallel across the power source 13. If there were a partial or total system failure during the initial series initiation due to an open or high resistance activator, than all but the affected activator would be activated with the transfer to parallel mode. Thus, a series activator failure will result in no more than a single failure rather than potentially a total system failure.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, it will be obvious that the invention can be used with systems having more than three suppressor units by merely increasing the number of switches in the auxiliary circuit 21. It is therefore to be understood that within the scope of the appended claims the invention can be practised otherwise than as specifically described.

What is claimed is:

1. An electrical protection system comprising:

a plurality of suppressor units activatable to suppress an abnormal condition;

a plurality of electrical current responsive activators, one associated with each of said suppressor units and adapted to induce activation thereof;

electrical current supply means;

control circuit means connecting said activators in series and comprising actuator means for initiating activating current flow from said supply means to said series connected activators; and

auxiliary circuit means comprising switch means for connecting said activators in parallel in response to initiation of activating current flow by said actuator means.

2. A system according to claim 1 wherein said auxiliary circuit means comprises delay means for delaying connection of said activators in parallel after initiation of activating current flow by said actuator means.

3. A system according to claim 2 wherein said suppressor units comprise vessels containing a fire suppressing agent.

4. A system according to claim 3 wherein said activators comprise explosive squibs for inducing release of said suppressing agent from said vessels.

5. A system according to claim 1 wherein said actuator means comprises a sensor means for detecting said abnormal condition.

6. A system according to claim 5 wherein said auxiliary circuit means comprises delay means for delaying connection of said activators in parallel after initiation of activating current flow by said actuator means.

7. A system according to claim 6 wherein said suppressor units comprise vessels containing a fire suppressing agent.

8. A system according to claim 7 wherein said sensor means comprises a thermal detection means.

9. A system according to claim 1 including supervision circuit means for supplying a supervisory current flow through said series connected activators, said supervisory current flow being insufficient to activate said activators, and wherein said supervision circuit means comprises indicator means for monitoring said supervisory current flow.

10. A system according to claim 9 wherein said auxiliary circuit means comprises delay means for delaying connection of said activators in parallel after initiation of activating current flow by said actuator means.

1 1. A system according to claim 10 wherein said suppressor units comprise vessels containing a fire suppressing agent.

12. A system according to claim 11 wherein said actuator means comprises a sensor means for detecting said abnormal condition. 

1. An electrical protection system comprising: a plurality of suppressor units activatable to suppress an abnormal condition; a plurality of electrical current responsive activators, one associated with each of said suppressor units and adapted to induce activation thereof; electrical current supply means; control circuit means connecting said activators in series and comprising actuator means for initiating activating current flow from said supply means to said series connected activators; and auxiliary circuit means comprising switch means for connecting said activators in parallel in response to initiation of activating current flow by said actuator means.
 2. A system according to claim 1 wherein said auxiliary circuit means comprises delay means for delaying connection of said activators in parallel after initiation of activating current flow by said actuator means.
 3. A system according to claim 2 wherein said suppressor units comprise vessels containing a fire suppressing agent.
 4. A system according to claim 3 wherein said activators comprise explosive squibs for inducing release of said suppressing agent from said vessels.
 5. A system according to claim 1 wherein said actuator means comprises a sensor means for detecting said abnormal condition.
 6. A system according to claim 5 wherein said auxiliary circuit means comprises delay means for delaying connection of said activators in parallel after initiation of activating current flow by said actuator means.
 7. A system according to claim 6 wherein said suppressor units comprise vessels containing a fire suppressing agent.
 8. A system according to claim 7 wherein said sensor means comprises a thermal detection means.
 9. A system according to claim 1 including supervision circuit means for supplying a supervisory current flow through said series connected activators, said supervisory current flow being insufficient to activate said activators, and wherein said supervision circuit means comprises indicator means for monitoring said supervisory current flow.
 10. A system according to claim 9 wherein said auxiliary circuit means comprises delay means for delaying connection of said activators in parallel after initiation of activating current flow by said actuator means.
 11. A system according to claim 10 wherein said suppressor units comprise vessels containing a fire suppressing agent.
 12. A system according to claim 11 wherein said actuator means comprises a sensor means for detecting said abnormal condition. 